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RF AMMETERS

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  • ve6pg
    HI FROM TIM..I KNOW THIS ISNT LOOP TYPE STUFF,BUT I M LOOKING FOR A DWG FOR HOMEBREW RF AMMETERS...NOT COAXIAL,BUT STRAIGHT THRU,OPEN WIRE TYPE...ANY
    Message 1 of 9 , Aug 5, 2005
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      HI FROM TIM..I KNOW THIS ISNT LOOP TYPE STUFF,BUT I'M LOOKING FOR A
      DWG FOR HOMEBREW RF AMMETERS...NOT COAXIAL,BUT STRAIGHT THRU,OPEN WIRE
      TYPE...ANY IDEAS?..SK..
    • gplynas
      What frequency range and current range is required? Is remote sensing required? Regards, Paul WA5LFY ... WIRE
      Message 2 of 9 , Aug 6, 2005
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        What frequency range and current range is required? Is remote sensing
        required?
        Regards,
        Paul
        WA5LFY

        --- In loopantennas@yahoogroups.com, "ve6pg" <ve6pg@y...> wrote:
        > HI FROM TIM..I KNOW THIS ISNT LOOP TYPE STUFF,BUT I'M LOOKING FOR A
        > DWG FOR HOMEBREW RF AMMETERS...NOT COAXIAL,BUT STRAIGHT THRU,OPEN
        WIRE
        > TYPE...ANY IDEAS?..SK..
      • Ken Javor
        I would use an rf current probe. You can get them on e-bay anywhere from $50 to $300 on e-bay. Frequency ranges (various models) cover 30 Hz to 1 GHz. From:
        Message 3 of 9 , Aug 6, 2005
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          I would use an rf current probe. You can get them on e-bay anywhere from
          $50 to $300 on e-bay. Frequency ranges (various models) cover 30 Hz to 1
          GHz.

          From: "ve6pg" <ve6pg@...>
          Reply-To: loopantennas@yahoogroups.com
          Date: Sat, 06 Aug 2005 04:01:34 -0000
          To: loopantennas@yahoogroups.com
          Subject: [loopantennas] RF AMMETERS


          HI FROM TIM..I KNOW THIS ISNT LOOP TYPE STUFF,BUT I'M LOOKING FOR A
          DWG FOR HOMEBREW RF AMMETERS...NOT COAXIAL,BUT STRAIGHT THRU,OPEN WIRE
          TYPE...ANY IDEAS?..SK..





          If you've got links, post them in the Links section!
          http://groups.yahoo.com/group/loopantennas/links

          For uploading images, I prefer the Files section since Photos only allows
          everyone (except the uploader and moderators) to see a max of 300x400.
          http://groups.yahoo.com/group/loopantennas/files

          Put them in the appropriate folder, or create one.





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          [Non-text portions of this message have been removed]
        • tim smith
          ...$50 TO $300.00..NEVER...I M A HAM..I BUILD THINGS...SK.. ... ...
          Message 4 of 9 , Aug 6, 2005
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            ...$50 TO $300.00..NEVER...I'M A HAM..I BUILD
            THINGS...SK..

            --- Ken Javor <ken.javor@...> wrote:

            > I would use an rf current probe. You can get them
            > on e-bay anywhere from
            > $50 to $300 on e-bay. Frequency ranges (various
            > models) cover 30 Hz to 1
            > GHz.
            >
            > From: "ve6pg" <ve6pg@...>
            > Reply-To: loopantennas@yahoogroups.com
            > Date: Sat, 06 Aug 2005 04:01:34 -0000
            > To: loopantennas@yahoogroups.com
            > Subject: [loopantennas] RF AMMETERS
            >
            >
            > HI FROM TIM..I KNOW THIS ISNT LOOP TYPE STUFF,BUT
            > I'M LOOKING FOR A
            > DWG FOR HOMEBREW RF AMMETERS...NOT COAXIAL,BUT
            > STRAIGHT THRU,OPEN WIRE
            > TYPE...ANY IDEAS?..SK..
            >
            >
            >
            >
            >
            > If you've got links, post them in the Links section!
            > http://groups.yahoo.com/group/loopantennas/links
            >
            > For uploading images, I prefer the Files section
            > since Photos only allows
            > everyone (except the uploader and moderators) to see
            > a max of 300x400.
            > http://groups.yahoo.com/group/loopantennas/files
            >
            > Put them in the appropriate folder, or create one.
            >
            >
            >
            >
            >
            > YAHOO! GROUPS LINKS
            >
            > Visit your group "loopantennas
            > <http://groups.yahoo.com/group/loopantennas>
            > " on the web.
            >
            > To unsubscribe from this group, send an email to:
            > loopantennas-unsubscribe@yahoogroups.com
            >
            <mailto:loopantennas-unsubscribe@yahoogroups.com?subject=Unsubscribe>
            >
            > Your use of Yahoo! Groups is subject to the Yahoo!
            > Terms of Service
            > <http://docs.yahoo.com/info/terms/> .
            >
            >
            >
            >
            >
            >
            >
            >
            >
            > [Non-text portions of this message have been
            > removed]
            >
            >


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          • gplynas
            A simple RF ammeter for detecting line/antenna current can be constructed by making a small loop of about 3 inch diameter and feeding it series to a diode
            Message 5 of 9 , Aug 6, 2005
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              A simple RF ammeter for detecting line/antenna current can be
              constructed by making a small loop of about 3 inch diameter and
              feeding it series to a diode 1N34A) detector and micro-ammeter. If
              greater sensitivity is desired, the loop can be fed to an Analog
              Devices AD8310 (or equivalent) log amp/detector. This is a self-
              contained 90 dB log amp with a dc to 400 MHz frequency response and an
              output which could directly drive a meter. It can be powered from a
              supply of about 8 mA between 2.7 and 5.5 volts, so a small self-
              contained very accurate meter circuit could be created. Suspend the
              loop from an insulating hook below the RF line. If you really want to
              get fancy, you could connect the AD8310 to a V/F converter and send
              the signal down through a fiber-optic link to a hand-held meter. Go
              to the Analog Devices web site and search for AD8310. These are some
              of the same log amps which are used to measure your signal strength at
              the local cell-phone tower.
              Regards,
              Paul
              WA5LFY


              --- In loopantennas@yahoogroups.com, "ve6pg" <ve6pg@y...> wrote:
              > HI FROM TIM..I KNOW THIS ISNT LOOP TYPE STUFF,BUT I'M LOOKING FOR A
              > DWG FOR HOMEBREW RF AMMETERS...NOT COAXIAL,BUT STRAIGHT THRU,OPEN
              WIRE
              > TYPE...ANY IDEAS?..SK..
            • Ken Javor
              Fine, build a current probe. You just need the right ferrite core for the job, some wire and an electrostatic shield so that the probe output is proportional
              Message 6 of 9 , Aug 6, 2005
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                Fine, build a current probe. You just need the right ferrite core for the
                job, some wire and an electrostatic shield so that the probe output is
                proportional to current, not potential. You will have to calibrate the
                thing when you are done. That means passing an accurately known current
                through it and measuring its output. Since you don't know the probes source
                impedance I would keep the connecting transmission line between probe and
                measurement device electrically short, to avoid vswr-related inaccuracy. By
                the time you get done, you will have more time and money into it than if you
                had just bought one, but it sounds as if that isn't a problem for you.

                From: tim smith <ve6pg@...>
                Reply-To: loopantennas@yahoogroups.com
                Date: Sat, 6 Aug 2005 11:31:05 -0700 (PDT)
                To: loopantennas@yahoogroups.com
                Subject: Re: [loopantennas] RF AMMETERS


                ...$50 TO $300.00..NEVER...I'M A HAM..I BUILD
                THINGS...SK..

                --- Ken Javor <ken.javor@...> wrote:

                > I would use an rf current probe. You can get them
                > on e-bay anywhere from
                > $50 to $300 on e-bay. Frequency ranges (various
                > models) cover 30 Hz to 1
                > GHz.
                >
                > From: "ve6pg" <ve6pg@...>
                > Reply-To: loopantennas@yahoogroups.com
                > Date: Sat, 06 Aug 2005 04:01:34 -0000
                > To: loopantennas@yahoogroups.com
                > Subject: [loopantennas] RF AMMETERS
                >
                >
                > HI FROM TIM..I KNOW THIS ISNT LOOP TYPE STUFF,BUT
                > I'M LOOKING FOR A
                > DWG FOR HOMEBREW RF AMMETERS...NOT COAXIAL,BUT
                > STRAIGHT THRU,OPEN WIRE
                > TYPE...ANY IDEAS?..SK..
                >
                >
                >
                >
                >
                > If you've got links, post them in the Links section!
                > http://groups.yahoo.com/group/loopantennas/links
                >
                > For uploading images, I prefer the Files section
                > since Photos only allows
                > everyone (except the uploader and moderators) to see
                > a max of 300x400.
                > http://groups.yahoo.com/group/loopantennas/files
                >
                > Put them in the appropriate folder, or create one.
                >
                >
                >
                >
                >
                > YAHOO! GROUPS LINKS
                >
                > Visit your group "loopantennas
                > <http://groups.yahoo.com/group/loopantennas>
                > " on the web.
                >
                > To unsubscribe from this group, send an email to:
                > loopantennas-unsubscribe@yahoogroups.com
                >
                <mailto:loopantennas-unsubscribe@yahoogroups.com?subject=Unsubscribe>
                >
                > Your use of Yahoo! Groups is subject to the Yahoo!
                > Terms of Service
                > <http://docs.yahoo.com/info/terms/> .
                >
                >
                >
                >
                >
                >
                >
                >
                >
                > [Non-text portions of this message have been
                > removed]
                >
                >


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                If you've got links, post them in the Links section!
                http://groups.yahoo.com/group/loopantennas/links

                For uploading images, I prefer the Files section since Photos only allows
                everyone (except the uploader and moderators) to see a max of 300x400.
                http://groups.yahoo.com/group/loopantennas/files

                Put them in the appropriate folder, or create one.





                YAHOO! GROUPS LINKS

                Visit your group "loopantennas <http://groups.yahoo.com/group/loopantennas>
                " on the web.

                To unsubscribe from this group, send an email to:
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                <mailto:loopantennas-unsubscribe@yahoogroups.com?subject=Unsubscribe>

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                <http://docs.yahoo.com/info/terms/> .









                [Non-text portions of this message have been removed]
              • tim smith
                OK..I UNDERSTAND,..THE PURPOSE OF THE RF AMMETER IS YES,TO MEASURE CURRENT THRU THE CORE,OR PICK-UP,BE IT A ENERGIZED LINE,OR AS IN PROFESSIONAL SYSTEMS,A
                Message 7 of 9 , Aug 6, 2005
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                  OK..I UNDERSTAND,..THE PURPOSE OF THE RF AMMETER IS
                  YES,TO MEASURE CURRENT THRU THE CORE,OR PICK-UP,BE IT
                  A ENERGIZED LINE,OR AS IN PROFESSIONAL SYSTEMS,A
                  THERMO-COUPLE,OF OF COURSE DIS-SIMILAR METALS. BUT
                  THIS PURPOSE IS NOT FOR ACCURATE CURRENT READINGS,BUT
                  AS AN INDICATOR OF BALANCED RF IN OPEN WIRE 600 OHM
                  LINE. YOUR TYPICAL HAM ANTENNA TUNER (JUNK),WILL TUNE
                  FOR A MINIMUM SWR,AS READ ON A BRIDGE,BUT THE LINE IS
                  NOT BALANCED. WHEN A TUNER HAS A BALUN THAT IS
                  WOUND,THE IDEA IS TO ACHIEVE A REASONABLE MATCH
                  FROM,SAY,600 OHMS (BALANCED)TO TRANSMITTER/RECEIVER OF
                  APPROX 52 OHMS (DEPENDANT ON FREQUENCY RESONANCE OF
                  THE FINAL TUNED TANK CIRCUIT)UNBALANCED.THE PROBLEM
                  THAT ARISES IS THAT,THE TRANSMITTER IS FOOLED TO SEE
                  FINAL IMPEDANCE AT 52OHMS...OK,FINE,BUT WHY RUN OPEN
                  WIRE LINE,WHEN IT IS NOT TRULY BALANCED?..THE "Q" THAT
                  ONE HAS TO DEAL WITH WHEN DEALING WITH ANTENNAS THAT
                  ARE OFF-RESONANCE,IS A LARGE FACTOR IN DETERMINING
                  BALANCE. TO OVERCOME THIS,A LINK COUPLED TUNER,WITH A
                  LARGE COIL,TO A 600PF 5KV VARIABLE CAPACITOR WILL
                  (DOES) TUNE THE ANTENNA FAR SUPERIOR TO COMMERCIAL
                  TUNERS..OK.,NOW WE HAVE TO TUNE THE FINAL TANK,HAVE
                  DECENT PLATE CURRENT,BUFFER/OSCILLATOR/GRID DRIVE.THE
                  ANTENNA IS THEN TUNED FOR LOW SWR,AND THEN WE HAVE TO
                  CHECK THE CURRENT ON BOTH LINES AT THE SAME TIME OF
                  TRANSMISSION.DUAL METERS WITH EQUAL RESISTANCE AND
                  ACTUAL CAPACITANCE HAVE TO BE INCORPORATED,IN ORDER TO
                  SEE IF THE TRANSMITTED CARRIER IS IN
                  BALANCE.ADJUSTMENTS MADE TO THE TUNER ARE THEN CARRIED
                  OUT,TO REACH TRUE BALANCE.THESE ARE THE TAPS ON THE
                  TUNER'S COIL,AND LINK-COUPLING. THIS IS THE ONLY REAL
                  WAY TO TUNE TO ACTUAL VISUAL BALANCE...SK..

                  --- Ken Javor <ken.javor@...> wrote:

                  > Fine, build a current probe. You just need the
                  > right ferrite core for the
                  > job, some wire and an electrostatic shield so that
                  > the probe output is
                  > proportional to current, not potential. You will
                  > have to calibrate the
                  > thing when you are done. That means passing an
                  > accurately known current
                  > through it and measuring its output. Since you
                  > don't know the probes source
                  > impedance I would keep the connecting transmission
                  > line between probe and
                  > measurement device electrically short, to avoid
                  > vswr-related inaccuracy. By
                  > the time you get done, you will have more time and
                  > money into it than if you
                  > had just bought one, but it sounds as if that isn't
                  > a problem for you.
                  >
                  > From: tim smith <ve6pg@...>
                  > Reply-To: loopantennas@yahoogroups.com
                  > Date: Sat, 6 Aug 2005 11:31:05 -0700 (PDT)
                  > To: loopantennas@yahoogroups.com
                  > Subject: Re: [loopantennas] RF AMMETERS
                  >
                  >
                  > ...$50 TO $300.00..NEVER...I'M A HAM..I BUILD
                  > THINGS...SK..
                  >
                  > --- Ken Javor <ken.javor@...> wrote:
                  >
                  > > I would use an rf current probe. You can get them
                  > > on e-bay anywhere from
                  > > $50 to $300 on e-bay. Frequency ranges (various
                  > > models) cover 30 Hz to 1
                  > > GHz.
                  > >
                  > > From: "ve6pg" <ve6pg@...>
                  > > Reply-To: loopantennas@yahoogroups.com
                  > > Date: Sat, 06 Aug 2005 04:01:34 -0000
                  > > To: loopantennas@yahoogroups.com
                  > > Subject: [loopantennas] RF AMMETERS
                  > >
                  > >
                  > > HI FROM TIM..I KNOW THIS ISNT LOOP TYPE STUFF,BUT
                  > > I'M LOOKING FOR A
                  > > DWG FOR HOMEBREW RF AMMETERS...NOT COAXIAL,BUT
                  > > STRAIGHT THRU,OPEN WIRE
                  > > TYPE...ANY IDEAS?..SK..
                  > >
                  > >
                  > >
                  > >
                  > >
                  > > If you've got links, post them in the Links
                  > section!
                  > > http://groups.yahoo.com/group/loopantennas/links
                  > >
                  > > For uploading images, I prefer the Files section
                  > > since Photos only allows
                  > > everyone (except the uploader and moderators) to
                  > see
                  > > a max of 300x400.
                  > > http://groups.yahoo.com/group/loopantennas/files
                  > >
                  > > Put them in the appropriate folder, or create one.
                  > >
                  > >
                  > >
                  > >
                  > >
                  > > YAHOO! GROUPS LINKS
                  > >
                  > > Visit your group "loopantennas
                  > > <http://groups.yahoo.com/group/loopantennas>
                  > > " on the web.
                  > >
                  > > To unsubscribe from this group, send an email to:
                  > > loopantennas-unsubscribe@yahoogroups.com
                  > >
                  >
                  <mailto:loopantennas-unsubscribe@yahoogroups.com?subject=Unsubscribe>
                  > >
                  > > Your use of Yahoo! Groups is subject to the
                  > Yahoo!
                  > > Terms of Service
                  > > <http://docs.yahoo.com/info/terms/> .
                  > >
                  > >
                  > >
                  > >
                  > >
                  > >
                  > >
                  > >
                  > >
                  > > [Non-text portions of this message have been
                  > > removed]
                  > >
                  > >
                  >
                  >
                  > __________________________________________________
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                  >
                  > If you've got links, post them in the Links section!
                  > http://groups.yahoo.com/group/loopantennas/links
                  >
                  > For uploading images, I prefer the Files section
                  > since Photos only allows
                  > everyone (except the uploader and moderators) to see
                  > a max of 300x400.
                  > http://groups.yahoo.com/group/loopantennas/files
                  >
                  > Put them in the appropriate folder, or create one.
                  >
                  >
                  >
                  >
                  >
                  > YAHOO! GROUPS LINKS
                  >
                  > Visit your group "loopantennas
                  > <http://groups.yahoo.com/group/loopantennas>
                  > " on the web.
                  >
                  > To unsubscribe from this group, send an email to:
                  > loopantennas-unsubscribe@yahoogroups.com
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                  >
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                • Steve Baker
                  stop yelling! ... ...
                  Message 8 of 9 , Aug 6, 2005
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                    stop yelling!

                    --- tim smith <ve6pg@...> wrote:

                    > OK..I UNDERSTAND,..THE PURPOSE OF THE RF AMMETER IS
                    > YES,TO MEASURE CURRENT THRU THE CORE,OR PICK-UP,BE
                    > IT
                    > A ENERGIZED LINE,OR AS IN PROFESSIONAL SYSTEMS,A
                    > THERMO-COUPLE,OF OF COURSE DIS-SIMILAR METALS. BUT
                    > THIS PURPOSE IS NOT FOR ACCURATE CURRENT
                    > READINGS,BUT
                    > AS AN INDICATOR OF BALANCED RF IN OPEN WIRE 600 OHM
                    > LINE. YOUR TYPICAL HAM ANTENNA TUNER (JUNK),WILL
                    > TUNE
                    > FOR A MINIMUM SWR,AS READ ON A BRIDGE,BUT THE LINE
                    > IS
                    > NOT BALANCED. WHEN A TUNER HAS A BALUN THAT IS
                    > WOUND,THE IDEA IS TO ACHIEVE A REASONABLE MATCH
                    > FROM,SAY,600 OHMS (BALANCED)TO TRANSMITTER/RECEIVER
                    > OF
                    > APPROX 52 OHMS (DEPENDANT ON FREQUENCY RESONANCE OF
                    > THE FINAL TUNED TANK CIRCUIT)UNBALANCED.THE PROBLEM
                    > THAT ARISES IS THAT,THE TRANSMITTER IS FOOLED TO SEE
                    > FINAL IMPEDANCE AT 52OHMS...OK,FINE,BUT WHY RUN OPEN
                    > WIRE LINE,WHEN IT IS NOT TRULY BALANCED?..THE "Q"
                    > THAT
                    > ONE HAS TO DEAL WITH WHEN DEALING WITH ANTENNAS THAT
                    > ARE OFF-RESONANCE,IS A LARGE FACTOR IN DETERMINING
                    > BALANCE. TO OVERCOME THIS,A LINK COUPLED TUNER,WITH
                    > A
                    > LARGE COIL,TO A 600PF 5KV VARIABLE CAPACITOR WILL
                    > (DOES) TUNE THE ANTENNA FAR SUPERIOR TO COMMERCIAL
                    > TUNERS..OK.,NOW WE HAVE TO TUNE THE FINAL TANK,HAVE
                    > DECENT PLATE CURRENT,BUFFER/OSCILLATOR/GRID
                    > DRIVE.THE
                    > ANTENNA IS THEN TUNED FOR LOW SWR,AND THEN WE HAVE
                    > TO
                    > CHECK THE CURRENT ON BOTH LINES AT THE SAME TIME OF
                    > TRANSMISSION.DUAL METERS WITH EQUAL RESISTANCE AND
                    > ACTUAL CAPACITANCE HAVE TO BE INCORPORATED,IN ORDER
                    > TO
                    > SEE IF THE TRANSMITTED CARRIER IS IN
                    > BALANCE.ADJUSTMENTS MADE TO THE TUNER ARE THEN
                    > CARRIED
                    > OUT,TO REACH TRUE BALANCE.THESE ARE THE TAPS ON THE
                    > TUNER'S COIL,AND LINK-COUPLING. THIS IS THE ONLY
                    > REAL
                    > WAY TO TUNE TO ACTUAL VISUAL BALANCE...SK..
                    >
                    > --- Ken Javor <ken.javor@...> wrote:
                    >
                    > > Fine, build a current probe. You just need the
                    > > right ferrite core for the
                    > > job, some wire and an electrostatic shield so that
                    > > the probe output is
                    > > proportional to current, not potential. You will
                    > > have to calibrate the
                    > > thing when you are done. That means passing an
                    > > accurately known current
                    > > through it and measuring its output. Since you
                    > > don't know the probes source
                    > > impedance I would keep the connecting transmission
                    > > line between probe and
                    > > measurement device electrically short, to avoid
                    > > vswr-related inaccuracy. By
                    > > the time you get done, you will have more time and
                    > > money into it than if you
                    > > had just bought one, but it sounds as if that
                    > isn't
                    > > a problem for you.
                    > >
                    > > From: tim smith <ve6pg@...>
                    > > Reply-To: loopantennas@yahoogroups.com
                    > > Date: Sat, 6 Aug 2005 11:31:05 -0700 (PDT)
                    > > To: loopantennas@yahoogroups.com
                    > > Subject: Re: [loopantennas] RF AMMETERS
                    > >
                    > >
                    > > ...$50 TO $300.00..NEVER...I'M A HAM..I BUILD
                    > > THINGS...SK..
                    > >
                    > > --- Ken Javor <ken.javor@...> wrote:
                    > >
                    > > > I would use an rf current probe. You can get
                    > them
                    > > > on e-bay anywhere from
                    > > > $50 to $300 on e-bay. Frequency ranges (various
                    > > > models) cover 30 Hz to 1
                    > > > GHz.
                    > > >
                    > > > From: "ve6pg" <ve6pg@...>
                    > > > Reply-To: loopantennas@yahoogroups.com
                    > > > Date: Sat, 06 Aug 2005 04:01:34 -0000
                    > > > To: loopantennas@yahoogroups.com
                    > > > Subject: [loopantennas] RF AMMETERS
                    > > >
                    > > >
                    > > > HI FROM TIM..I KNOW THIS ISNT LOOP TYPE
                    > STUFF,BUT
                    > > > I'M LOOKING FOR A
                    > > > DWG FOR HOMEBREW RF AMMETERS...NOT COAXIAL,BUT
                    > > > STRAIGHT THRU,OPEN WIRE
                    > > > TYPE...ANY IDEAS?..SK..
                    > > >
                    > > >
                    > > >
                    > > >
                    > > >
                    > > > If you've got links, post them in the Links
                    > > section!
                    > > > http://groups.yahoo.com/group/loopantennas/links
                    > > >
                    > > > For uploading images, I prefer the Files section
                    > > > since Photos only allows
                    > > > everyone (except the uploader and moderators) to
                    > > see
                    > > > a max of 300x400.
                    > > > http://groups.yahoo.com/group/loopantennas/files
                    > > >
                    > > > Put them in the appropriate folder, or create
                    > one.
                    > > >
                    > > >
                    > > >
                    > > >
                    > > >
                    > > > YAHOO! GROUPS LINKS
                    > > >
                    > > > Visit your group "loopantennas
                    > > > <http://groups.yahoo.com/group/loopantennas>
                    > > > " on the web.
                    > > >
                    > > > To unsubscribe from this group, send an email
                    > to:
                    > > > loopantennas-unsubscribe@yahoogroups.com
                    > > >
                    > >
                    >
                    <mailto:loopantennas-unsubscribe@yahoogroups.com?subject=Unsubscribe>
                    > > >
                    > > > Your use of Yahoo! Groups is subject to the
                    > > Yahoo!
                    > > > Terms of Service
                    > > > <http://docs.yahoo.com/info/terms/> .
                    > > >
                    > > >
                    > > >
                    > > >
                    > > >
                    > > >
                    > > >
                    > > >
                    > > >
                    > > > [Non-text portions of this message have been
                    > > > removed]
                    > > >
                    > > >
                    > >
                    > >
                    > > __________________________________________________
                    > > Do You Yahoo!?
                    > > Tired of spam? Yahoo! Mail has the best spam
                    > > protection around
                    > > http://mail.yahoo.com
                    > >
                    > >
                    > > If you've got links, post them in the Links
                    > section!
                    > > http://groups.yahoo.com/group/loopantennas/links
                    > >
                    > > For uploading images, I prefer the Files section
                    > > since Photos only allows
                    > > everyone (except the uploader and moderators) to
                    > see
                    > > a max of 300x400.
                    > > http://groups.yahoo.com/group/loopantennas/files
                    > >
                    > > Put them in the appropriate folder, or create one.
                    > >
                    > >
                    > >
                    > >
                    > >
                    > > YAHOO! GROUPS LINKS
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                  • Ken Javor
                    If the condition you are looking for is equal and opposite currents on both transmission line conductors, then the current probe is even more useful. Simply
                    Message 9 of 9 , Aug 6, 2005
                    • 0 Attachment
                      If the condition you are looking for is equal and opposite currents on both
                      transmission line conductors, then the current probe is even more useful.
                      Simply place it around both conductors simultaneously. The current probe
                      output will be proportional to the unbalanced current flowing through the
                      window. If the current on both transmission line conductors were exactly
                      equal and opposite in phase, the current probe output would be zero. That
                      is assuming the electrostatic shielding is sufficient so that capacitive
                      coupling does not give a false indication.

                      From: tim smith <ve6pg@...>
                      Reply-To: loopantennas@yahoogroups.com
                      Date: Sat, 6 Aug 2005 15:57:13 -0700 (PDT)
                      To: loopantennas@yahoogroups.com
                      Subject: Re: [loopantennas] RF AMMETERS


                      OK..I UNDERSTAND,..THE PURPOSE OF THE RF AMMETER IS
                      YES,TO MEASURE CURRENT THRU THE CORE,OR PICK-UP,BE IT
                      A ENERGIZED LINE,OR AS IN PROFESSIONAL SYSTEMS,A
                      THERMO-COUPLE,OF OF COURSE DIS-SIMILAR METALS. BUT
                      THIS PURPOSE IS NOT FOR ACCURATE CURRENT READINGS,BUT
                      AS AN INDICATOR OF BALANCED RF IN OPEN WIRE 600 OHM
                      LINE. YOUR TYPICAL HAM ANTENNA TUNER (JUNK),WILL TUNE
                      FOR A MINIMUM SWR,AS READ ON A BRIDGE,BUT THE LINE IS
                      NOT BALANCED. WHEN A TUNER HAS A BALUN THAT IS
                      WOUND,THE IDEA IS TO ACHIEVE A REASONABLE MATCH
                      FROM,SAY,600 OHMS (BALANCED)TO TRANSMITTER/RECEIVER OF
                      APPROX 52 OHMS (DEPENDANT ON FREQUENCY RESONANCE OF
                      THE FINAL TUNED TANK CIRCUIT)UNBALANCED.THE PROBLEM
                      THAT ARISES IS THAT,THE TRANSMITTER IS FOOLED TO SEE
                      FINAL IMPEDANCE AT 52OHMS...OK,FINE,BUT WHY RUN OPEN
                      WIRE LINE,WHEN IT IS NOT TRULY BALANCED?..THE "Q" THAT
                      ONE HAS TO DEAL WITH WHEN DEALING WITH ANTENNAS THAT
                      ARE OFF-RESONANCE,IS A LARGE FACTOR IN DETERMINING
                      BALANCE. TO OVERCOME THIS,A LINK COUPLED TUNER,WITH A
                      LARGE COIL,TO A 600PF 5KV VARIABLE CAPACITOR WILL
                      (DOES) TUNE THE ANTENNA FAR SUPERIOR TO COMMERCIAL
                      TUNERS..OK.,NOW WE HAVE TO TUNE THE FINAL TANK,HAVE
                      DECENT PLATE CURRENT,BUFFER/OSCILLATOR/GRID DRIVE.THE
                      ANTENNA IS THEN TUNED FOR LOW SWR,AND THEN WE HAVE TO
                      CHECK THE CURRENT ON BOTH LINES AT THE SAME TIME OF
                      TRANSMISSION.DUAL METERS WITH EQUAL RESISTANCE AND
                      ACTUAL CAPACITANCE HAVE TO BE INCORPORATED,IN ORDER TO
                      SEE IF THE TRANSMITTED CARRIER IS IN
                      BALANCE.ADJUSTMENTS MADE TO THE TUNER ARE THEN CARRIED
                      OUT,TO REACH TRUE BALANCE.THESE ARE THE TAPS ON THE
                      TUNER'S COIL,AND LINK-COUPLING. THIS IS THE ONLY REAL
                      WAY TO TUNE TO ACTUAL VISUAL BALANCE...SK..

                      --- Ken Javor <ken.javor@...> wrote:

                      > Fine, build a current probe. You just need the
                      > right ferrite core for the
                      > job, some wire and an electrostatic shield so that
                      > the probe output is
                      > proportional to current, not potential. You will
                      > have to calibrate the
                      > thing when you are done. That means passing an
                      > accurately known current
                      > through it and measuring its output. Since you
                      > don't know the probes source
                      > impedance I would keep the connecting transmission
                      > line between probe and
                      > measurement device electrically short, to avoid
                      > vswr-related inaccuracy. By
                      > the time you get done, you will have more time and
                      > money into it than if you
                      > had just bought one, but it sounds as if that isn't
                      > a problem for you.
                      >
                      > From: tim smith <ve6pg@...>
                      > Reply-To: loopantennas@yahoogroups.com
                      > Date: Sat, 6 Aug 2005 11:31:05 -0700 (PDT)
                      > To: loopantennas@yahoogroups.com
                      > Subject: Re: [loopantennas] RF AMMETERS
                      >
                      >
                      > ...$50 TO $300.00..NEVER...I'M A HAM..I BUILD
                      > THINGS...SK..
                      >
                      > --- Ken Javor <ken.javor@...> wrote:
                      >
                      > > I would use an rf current probe. You can get them
                      > > on e-bay anywhere from
                      > > $50 to $300 on e-bay. Frequency ranges (various
                      > > models) cover 30 Hz to 1
                      > > GHz.
                      > >
                      > > From: "ve6pg" <ve6pg@...>
                      > > Reply-To: loopantennas@yahoogroups.com
                      > > Date: Sat, 06 Aug 2005 04:01:34 -0000
                      > > To: loopantennas@yahoogroups.com
                      > > Subject: [loopantennas] RF AMMETERS
                      > >
                      > >
                      > > HI FROM TIM..I KNOW THIS ISNT LOOP TYPE STUFF,BUT
                      > > I'M LOOKING FOR A
                      > > DWG FOR HOMEBREW RF AMMETERS...NOT COAXIAL,BUT
                      > > STRAIGHT THRU,OPEN WIRE
                      > > TYPE...ANY IDEAS?..SK..
                      > >
                      > >
                      > >
                      > >
                      > >
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